Bituminous compositions based on phosphoric derivatives

ABSTRACT

The invention relates to a package of performance additives for bitumen or bituminous compositions including an acidic adjuvant and a H 2 S scavenger chosen from organic or inorganic copper salts. The invention also relates to the use of said H 2 S scavenger in order to reduce the H 2 S emissions of bitumen or of a bituminous composition treated with the acidic adjuvant. The invention additionally relates to a process for the preparation of a bituminous composition. The preparation process according to the invention makes it possible to obtain bitumen/crosslinked polymer compositions having better mechanical and dynamic properties in comparison with the bitumen/crosslinked polymer compositions of the prior art, while substantially reducing the releases of hydrogen sulfide (H 2 S).

This is a continuation of application Ser. No. 15/036,161 filed May 12,2016, which is a National Stage Application of PCT/EP2014/073869 filedNov. 6, 2014, and claims the benefit of French Application No. 1361031filed Nov. 12, 2013. The entire disclosure of the prior applications arehereby incorporated by reference in their entirety.

TECHNICAL FIELD

The present invention belongs to the field of bituminous compositionsand their performance additives. More specifically, it relates tobituminous compositions comprising phosphoric derivatives and to theirprocess of preparation.

The invention also relates to the use of these bituminous compositionsin the fields of road applications, in particular in the manufacture ofroad binders, such as hot bituminous mixes, cold bituminous mixes,asphalts and surface coatings, and in the fields of industrialapplications, for example in the manufacture of internal and externalcoatings.

PRIOR ART

The use of bitumen in the manufacture of materials for road andindustrial applications has been known for a long time: bitumen is themain hydrocarbon binder used in the field of road construction or civilengineering. In order to be able to be used as binder in these differentapplications, the bitumen has to exhibit certain mechanical and dynamicproperties.

In general, conventional bitumens do not simultaneously exhibit all ofthe required qualities. Bituminous compositions are used in thepreparation of binders for various surface coatings and in particular asroad surface coatings, provided that these compositions exhibit, incombination, a certain number of mechanical and/or dynamiccharacteristics. The mechanical properties of bituminous compositionsare determined by standardized tests of the different mechanicalcharacteristics, such as the softening point, the penetrability and therheological characteristics in predetermined tension.

Numerous studies have related to the improvement in the mechanical,elastic and/or rheological properties of bituminous compositions.

It has been known for a long time that the addition of various polymersto these conventional bitumens makes it possible to favorably modify themechanical properties of the latter and to form bitumen/polymercompositions having mechanical qualities which are improved with respectto those of the bitumens alone.

In addition, it is known that the stability of the bitumen/polymercompositions can be improved by chemical coupling of the polymer to thebitumen. This chemical coupling, conventionally carried out bycrosslinking of the polymer, makes it possible in addition to broadenthe range of use of the bitumen/polymer compositions. Mention may bemade of the documents FR 2 376 188, FR 2 429 241, FR 2 528 439 and EP 0360 656 as examples of a process involving a random or block copolymerof styrene and of a conjugated diene crosslinked with sulfur. Thedocument FR 2 528 439 relates in particular to crosslinking with apolysulfide. The document EP 0 360 656 describes the use of asulfur-donating vulcanization accelerator used alone or in combinationwith chemically non-bonded sulfur and/or a polysulfide or anon-sulfur-donating vulcanization accelerator.

The bitumen/crosslinked polymer compositions thus obtained are knownunder the acronym “PmB”, for Polymer-modified Bitumen, or “PmA”, forPolymer-modified Asphalt. For reasons of clarity, we will use only theacronym PmB for the bitumen/crosslinked polymer compositions. Thecrosslinking of the bitumen/polymer compositions confers on them verygood properties in terms of stability on storage, cohesiveness,elongational capability and resistance to aging.

Phosphoric acid and/or polyphosphoric acid has been used since the 1970sto improve the rheological properties of bitumens or bituminouscompositions, in particular for increasing their consistency. Mentionmay be made, by way of example, of the document U.S. Pat. No. 3,751,278,which describes a manufacturing process employing phosphoric acid forincreasing the viscosity at high temperature without decreasing theconsistency at ambient temperature.

Some acidic adjuvants have also been used to obtain bitumen/polymercompositions having a reinforced multigrade nature. In patentapplication EP 703 949, the authors have in addition demonstrated thatthe mechanical and/or rheological properties could be improved; inparticular, the plasticity interval could be widened by using specificacidic inorganic adjuvants. The authors cite in particular phosphoricacids, sulfonic acids, sulfuric acids and their mixtures.

In the document WO9714753, the authors have shown that it is possible towiden the plasticity interval of the bitumen/sulfur-crosslinked polymercompositions by incorporating, in said compositions, an inorganicadjuvant of the acid or acid anhydride type after the phase ofcrosslinking with sulfur.

Another problem related to the use of bituminous compositions concernsthe release of hydrogen sulfide, denoted H₂S, during their process ofpreparation or their use. The emission of H₂S is greater for thebitumen/crosslinked polymer compositions as a result of the use ofsulfur-donating crosslinking agent in their process of preparation.Hydrogen sulfide (H₂S) is a colorless and toxic gas exhibiting acharacteristic odor at a very low concentration. For reasons of safetyand of environmental constraints, the reduction, indeed even thesuppression, of hydrogen sulfide emissions during the production ofbituminous compositions, in particular of bitumen/crosslinked polymercompositions, constitutes an industrial challenge.

Solutions have been provided in the literature for reducing hydrogensulfide emissions during the manufacture or the use of bituminouscompositions. In particular, the addition of an agent capable oftrapping hydrogen sulfide (H₂S) during the crosslinking of bituminouscompositions has been provided in order to overcome this disadvantage.Mention may be made, by way of example, of the organic or inorganicmetal salts described in the international application WO02005065177 ascapable of trapping H₂S. The process employed for reducing the releasesof H₂S consists in introducing, into a reactor containing a premixedbitumen/polymer composition, an organic or inorganic metal salt. Themetal salt, added in bulk to the reactor, is subsequently stirred in thereactor during the crosslinking reaction.

The applicant company has been interested in the effectiveness of theagents capable of neutralizing and/or trapping H₂S in the processes forthe preparation of bituminous compositions, in particularbitumen/crosslinked polymer compositions employing acidic inorganicadjuvants.

The object of the present invention is the improvement in the mechanicaland dynamic properties, in particular the plasticity interval, ofbituminous compositions, while reducing the risks of H₂S emissionsduring the preparation and/or the use of such bituminous compositions.

Another object of the invention is to obtain bituminous compositionswhich release low amounts of H₂S, preferably amounts of less then 10ppm, more preferably of less than or equal to 1 ppm, during thepreparation and/or the use (transportation, loading, unloading andstorage) of such bituminous compositions, it being understood that thetemperatures for preparation and/or use are conventionally between 90°C. and 200° C. and that the content of H₂S is measured according to aconventional method for assaying H₂S in the liquid phase.

The present invention also relates to a process for the preparation ofsuch bituminous compositions.

BRIEF DESCRIPTION

In the context of the preparation of bituminous compositions, theapplicant company has discovered that, surprisingly, the use of anacidic adjuvant has a negative effect on the effectiveness of certainagents capable of neutralizing and/or trapping hydrogen sulfide (H₂S).

In particular, the applicant company has demonstrated that the acidicadjuvant deactivates said agents capable of neutralizing and/or trappinghydrogen sulfide (H₂S).

The applicant company has additionally discovered that the selection ofcertain specific agents capable of neutralizing and/or trapping hydrogensulfide (H₂S) makes it possible to overcome this disadvantage. Thespecific combination of an acidic adjuvant and of an agent capable ofneutralizing and/or trapping hydrogen sulfide (H₂S) makes it possible toobtain a bituminous composition having reduced H₂S emissions whileimproving the mechanical and/or dynamic properties of said composition.The use of such a combination is particularly advantageous forbitumen/crosslinked polymer compositions.

The applicant company has also discovered that, in order to obtain thiscombined effect, the agent capable of neutralizing and/or trappinghydrogen sulfide (H₂S) and the acidic adjuvant can be used together orsuccessively, the order of introduction having no effect.

For reasons of simplicity, the term “H₂S scavenger” will be usedsystematically in the continuation of the present patent application torefer to an agent capable of neutralizing and/or trapping hydrogensulfide (H₂S).

Bituminous composition is understood to mean any bitumen compositioncomprising, in addition to the bitumen, at least one other constituent,for example an elastomer, and/or at least one additive.

According to the invention, the aim of the invention is achieved by apackage of performance additives for bitumen or bituminous compositionscomprising an acidic adjuvant chosen from phosphoric acids,polyphosphoric acids and their mixtures and a H₂S scavenger chosen fromorganic or inorganic copper salts.

The H₂S scavenger is advantageously chosen from copper salts from thegroup consisting of copper oxides, hydroxides, hydrates, carbonates,hydroxy carbonates, carboxylates, nitrates and phosphates and theirmixtures.

According to a specific embodiment, the H₂S scavenger is chosen fromcopper salts from the group consisting of copper oxides, hydroxides,carbonates, hydroxy carbonates and carboxylates and their mixtures.

According to a preferred specific embodiment, the H₂S scavenger ischosen from copper salts from the group consisting of copper oxides,hydroxides, carbonates and hydroxy carbonates and their mixtures.

According to the invention, the aim of the invention is also achieved bythe use of a H₂S scavenger in order to reduce the H₂S emissions ofbitumen or of a bituminous composition treated with an acidic adjuvant,said H₂S scavenger and said acidic adjuvant being as described above.

According to a specific embodiment, the use of a H₂S scavenger to reducethe H₂S emissions of bitumen or of a bituminous composition treated withan acidic adjuvant is such that the acidic adjuvant and the H₂Sscavenger are in the form of a package of additives as described above.

According to the invention, the aim of the invention is also achieved bya process for the preparation of a bituminous composition, in whichbitumen, an acidic adjuvant and a H₂S scavenger are brought intocontact, the operation being carried out at temperatures of between 90°C. and 200° C., preferably between 120° C. and 200° C. and morepreferably between 170° C. and 190° C. and with stirring for a period oftime of at least 10 minutes, advantageously of at least 2 hours,preferably between 20 minutes and 6 hours, more preferably between 30minutes and 2 hours, said H₂S scavenger and said acidic adjuvant beingas defined above.

According to a specific embodiment, the proportion of acidic adjuvant isbetween 0.05% and 15% by weight, preferably between 0.05% and 5% byweight and more preferably between 0.05% and 2% by weight, thepercentages by weight being calculated with respect to the total weightof the bituminous composition.

According to another specific embodiment, the proportion of H₂Sscavenger is between 0.05% and 5% by weight, preferably between 0.1% and3% by weight and more preferably between 0.1% and 1% by weight, thepercentages by weight being calculated with respect to the total weightof the bituminous composition.

According to an alternative form, the process comprises the heating ofthe bitumen at a temperature of between 90° C. and 200° C., preferablybetween 120° C. and 200° C. and more preferably between 170° C. and 190°C., for at least 10 minutes, preferably between 20 minutes and 6 hoursand more preferably between 30 minutes and 2 hours, with stirring,followed by the addition of the acidic adjuvant and of the H₂Sscavenger, the reaction medium subsequently being maintained attemperature for at least 10 minutes with stirring, preferably between 20minutes and 6 hours and more preferably between 30 minutes and 2 hours.

Advantageously, the process additionally comprises a stage of additionof 0.5% to 10% by weight, preferably between 1% and 6% by weight andmore preferably between 1.5% and 4% by weight of an elastomer, it beingunderstood that the bituminous composition is then a bitumen/polymercomposition and that the percentages by weight are calculated withrespect to the total weight of the bitumen/polymer composition.

According to a preferred specific embodiment, the elastomer is chosenfrom sulfur-crosslinkable elastomers and the process additionallycomprises a stage of crosslinking of said elastomer by a sulfur-donatingcoupling agent added in an amount capable of providing from 0.1% to 20%by weight, advantageously from 1% to 10% by weight, preferably from 1%to 6% by weight and more preferably from 2% to 5% by weight of freesulfur with respect to the weight of sulfur-crosslinkable elastomer insaid composition, it being understood that the bituminous composition isthen a bitumen/crosslinked polymer composition.

The sulfur-donating coupling agent is advantageously chosen from thegroup consisting of elemental sulfur, hydrocarbyl polysulfides,sulfur-donating vulcanization accelerators and the mixtures of suchproducts with one another and/or with non-sulfur-donating vulcanizationaccelerators.

According to a preferred alternative form, the elastomer is chosen fromrandom or block copolymers of a monovinylaromatic hydrocarbon and of aconjugated diene.

The elastomer advantageously comprises between 5% and 50% by weight,preferably between 15% and 40% by weight, of monovinylaromatichydrocarbon.

The elastomer is preferably chosen from random or block copolymers ofstyrene and of a conjugated diene.

According to a specific development, the weight-average molecular weightof the elastomer is between 10 000 and 600 000 daltons, preferablybetween 30 000 and 400 000 daltons.

According to the invention, the aim of the invention is also achieved bya bituminous composition capable of being obtained by the preparationprocess as defined above.

The invention also relates to a bituminous binder comprising abituminous composition as defined above.

The invention also relates to an asphalt comprising a bituminous binderas described above and inorganic and/or synthetic fillers.

In addition, the invention relates to a bituminous mix comprising abituminous binder as described above, aggregates and optionallyinorganic and/or synthetic fillers.

DETAILED DESCRIPTION

Other advantages and characteristics will emerge more clearly from thedescription which will follow, the specific embodiments of the inventionof which are given as nonlimiting examples.

According to a specific embodiment, a package of performance additivescomprises an acidic adjuvant and a H₂S scavenger.

Package of additives is understood to mean a composition comprising atleast two additives. The package of additives can comprise additivesalone or dispersed/dissolved in an inert solvent, in particular ofmineral oil type, according to processes well known in the field ofadditives for bitumen. In the field of additivation, the term “package”is commonly used to identify a composition of additives. The term“concentrate of additives” can also be employed to denote the package ofadditives, in particular when the latter is provided in the form of asolution.

Performance additives for bitumen or bituminous composition isunderstood to mean additives which are capable of being incorporated ina bituminous composition, for example in relation to theircompatibility, their solubility or their stability in said bitumen orsaid bituminous composition, and which confer on it improved properties,in comparison with the non-additivated bitumen or bituminouscomposition. These properties can be mechanical and/or dynamic and/orcan relate to environmental and safety problems, for example problems ofH₂S emissions.

The acidic adjuvant is preferably chosen from phosphoric acids,polyphosphoric acids and their mixtures.

Various grades of phosphoric acid and/or of polyphosphoric acidcomprising different amounts of orthophosphoric acid are commerciallyavailable. Commercial phosphoric acids generally comprise from 50% to200% of orthophosphoric acid.

The term “polyphosphoric acid” refers to concentrated grades ofphosphoric acid (H₃PO₄) of greater than 95%, generally between 97% and118%, where the percentage corresponds to the apparent concentration ofH₃PO₄. Polyphosphoric acid is represented by the formulaH_(n+2)P_(n)O_(3n+1) in which n≥2. Polyphosphoric acid is generally amixture of pyrophosphoric acid (n=2), triphosphoric acid (n=3) andhigher acids (n>3). Phosphoric and polyphosphoric acids can compriseother acids, such as sulfuric acid and/or hydrofluoric acid, asimpurities, at concentrations conventionally ranging up to 2%.

The H₂S scavenger is chosen from organic or inorganic copper salts.

A H₂S scavenger will advantageously be chosen from copper salts from thegroup consisting of copper oxides, hydroxides, hydrates, carbonates,hydroxy carbonates, carboxylates, nitrates and phosphates and theirmixtures.

According to a specific embodiment, the H₂S scavenger is chosen from thegroup consisting of copper oxides, hydroxides, carbonates, hydroxycarbonates and carboxylates and their mixtures.

According to a preferred specific embodiment, the H₂S scavenger ischosen from the group consisting of copper oxides, hydroxides,carbonates and hydroxy carbonates and their mixtures. Copper oxides andhydroxy carbonates are particularly effective.

The ratio by weight of the H₂S scavenger with respect to the acidicadjuvant can advantageously be between 1:300 and 100:1, preferablybetween 1:10 and 10:1 and more preferably between 1:10 and 5:1.

The package of performance additives can be composed solely of the H₂Sscavenger and of the acidic adjuvant, alone or as a mixture in one ormore inert solvents, it being understood that said H₂S scavenger andsaid acidic adjuvant can respectively comprise up to 2% by weight ofimpurities without, for all that, it being considered that they are notused alone. The solvent has to be inert with respect to the acidicadjuvant and/or the H₂S scavenger.

Generally, the amount of solvent in the package of additives is between1% and 95%, preferably between 10% and 90%, more preferably between 20%and 80% and more preferably still between 40% and 60% by weight, thepercentages by weight being calculated with respect to the total weightof said package of additives.

The inert solvent or solvents will preferably be chosen so as todissolve both the H₂S scavenger and the acidic adjuvant. For example,the solvent will be chosen from mineral oils.

Preferably, the package of additives is composed solely of the H₂Sscavenger and of the acidic adjuvant, the ratio by weight of the H₂Sscavenger with respect to the acidic adjuvant being as described above.Such a package of additives is stable on storage and can be addeddirectly during the preparation of the bitumen/crosslinked polymercomposition.

The package of additives can be used directly in the treatment of thebitumen or bituminous compositions. In particular, the package ofadditives can advantageously be used in the process for the preparationof bituminous compositions, preferably of bitumen/polymer compositionsand more preferably of bitumen/crosslinked polymer compositionsemploying a sulfur-donating coupling agent.

According to an alternative form, the H₂S scavenger and the acidicadjuvant as described above can be used separately in the treatment ofthe bitumen or bituminous compositions, in particular in the preparationof bitumen/polymer compositions and preferably of bitumen/crosslinkedpolymer compositions employing a sulfur-donating coupling agent.

According to a specific embodiment, a process for the preparation of abitumen/crosslinked polymer composition comprises a stage of treatmentwith the acidic adjuvant and the H₂S scavenger described above at atemperature of between 90° C. and 200° C., preferably between 120° C.and 200° C. and more preferably between 170° C. and 190° C., for aperiod of time of at least 10 minutes, preferably of between 20 minutesand 6 hours and more preferably of between 30 minutes and 2 hours.

According to a specific embodiment, the process for the preparation of abitumen/crosslinked polymer composition comprises, for example, thefollowing stages:

-   -   a bitumen and a sulfur-crosslinkable elastomer are introduced        into a reactor,    -   the mixture is stirred until a homogeneous bitumen/elastomer        mixture is obtained and is heated at a temperature of between        90° C. and 200° C., preferably between 120° C. and 200° C. and        more preferably between 170° C. and 190° C., for a period of        time of at least 10 minutes, preferably of between 20 minutes        and 6 hours and more preferably of between 1 hour and 5 hours,    -   said elastomer is crosslinked by addition of a sulfur-donating        coupling agent to the reaction medium in an amount suitable for        providing from 0.1% to 20% by weight, advantageously from 1% to        10% by weight, preferably from 1% to 6% by weight and more        preferably from 2% to 5% by weight of free sulfur, with respect        to the total weight of the elastomer, while keeping the reaction        medium stirred at a temperature of between 90° C. and 200° C.,        preferably between 120° C. and 200° C. and more preferably        between 170° C. and 190° C., for a period of time of at least 10        minutes, preferably of between 20 minutes and 6 hours and more        preferably of between 30 minutes and 2 hours,    -   the H₂S scavenger described above is added, the reaction medium        being maintained at a temperature of between 90° C. and 200° C.,        preferably between 120° C. and 200° C. and more preferably        between 170° C. and 190° C., for a period of time of at least 10        minutes, preferably of between 20 minutes and 6 hours and more        preferably of between 30 minutes and 2 hours,    -   the acidic adjurant described above is added, the reaction        medium being maintained at a temperature of between 90° C. and        200° C., preferably between 120° C. and 200° C. and more        preferably between 170° C. and 190° C., for a period of time of        at least 10 minutes, preferably of between 20 minutes and 6        hours and more preferably of between 30 minutes and 2 hours.

According to another specific embodiment, the process for thepreparation of a bitumen/crosslinked polymer composition comprises, forexample, the following stages:

-   -   a bitumen and a sulfur-crosslinkable elastomer are introduced        into a reactor,    -   the mixture is stirred until a homogeneous bitumen/elastomer        mixture is obtained and is heated at a temperature of between        90° C. and 200° C., preferably between 120° C. and 200° C. and        more preferably between 170° C. and 190° C., for a period of        time of at least 10 minutes, preferably of between 20 minutes        and 6 hours and more preferably of between 1 hour and 5 hours,    -   said elastomer is crosslinked by addition of a sulfur-donating        coupling agent to the reaction medium in an amount suitable for        providing from 0.1% to 20% by weight, advantageously from 1% to        10% by weight, preferably from 1% to 6% by weight and more        preferably from 2% to 5% by weight of free sulfur, with respect        to the total weight of the elastomer, while keeping the reaction        medium stirred at a temperature of between 90° C. and 200° C.,        preferably between 120° C. and 200° C. and more preferably        between 170° C. and 190° C., for a period of time of at least 10        minutes, preferably of between 20 minutes and 6 hours and more        preferably of between 30 minutes and 2 hours,    -   the acidic adjuvant and the H₂S scavenger described above are        added simultaneously, the reaction medium being maintained at a        temperature of between 90° C. and 200° C., preferably between        120° C. and 200° C. and more preferably between 170° C. and 190°        C., for a period of time of at least 10 minutes, preferably of        between 20 minutes and 6 hours and more preferably of between 30        minutes and 2 hours.

The simultaneous addition of the H₂S scavenger and of the acidicadjuvant has the advantage of reducing the duration of preparation ofthe bitumen/crosslinked polymer composition and of improving theplasticity interval of said composition. Use may advantageously be madeof the package of additives as described above in the stage ofsimultaneous addition of the acidic adjuvant and of the H₂S scavenger.

For each stage, the temperatures may or may not be identical.

The bitumen according to the present invention can comprise one or morebitumen bases. The bitumen bases can result from different sources.Mention may first of all be made of bitumen bases of natural origin,those present in natural bitumen or natural asphalt deposits orbituminous sands.

The bitumen bases can advantageously originate from the refining ofcrude oil, preferably from the atmospheric and/or vacuum distillation ofoil. The bitumen bases can optionally be blown, visbroken and/ordeasphalted.

The bitumen bases can be chosen from bitumens of hard grade or of softgrade.

The different bitumen bases obtained by the refining processes can becombined with one another in order to obtain the best technicalcompromise.

The bitumen bases used can also be chosen from bitumens fluxed byaddition of volatile solvents, of fluxes of petroleum origin and/or offluxes of plant origin.

The bitumen is advantageously chosen from road bitumens of grades 10/20to 160/220 and special bitumens of all grades.

The bitumen represents between 90% and 99.3% by weight, preferablybetween 94% and 99% by weight, of the bitumen/crosslinked polymercomposition.

The amount of acidic adjuvant added represents advantageously between0.05% and 15% by weight, preferably between 0.05% and 5% by weight andmore preferably between 0.05% and 2% by weight of the total weight ofthe bitumen/crosslinked polymer composition.

The amount of H₂S scavenger added represents advantageously between0.05% and 5% by weight, preferably between 0.1% and 3% by weight andmore preferably between 0.1% and 1% by weight of the total weight of thebitumen/crosslinked polymer composition.

In the specific embodiment described above, the acidic adjuvant can beincorporated in the bitumen/crosslinked polymer mixture before or afterthe H₂S scavenger, it also being possible for a simultaneousincorporation to be envisaged, in particular by addition of a package ofadditives as described above to the bitumen/crosslinked polymer mixture.

The amount of elastomer introduced into the reactor representsadvantageously between 0.5% and 10% by weight, preferably between 1% and6% by weight and more preferably between 1.5% and 4% by weight of thetotal weight of the bitumen/crosslinked polymer composition.

The weight-average molecular weight of the elastomer is advantageouslybetween 10 000 and 600 000 daltons, preferably between 30 000 and 400000 daltons.

The elastomer is preferably chosen from random or block copolymers of amonovinylaromatic hydrocarbon and of a conjugated diene. In particular,the elastomer advantageously comprises between 5% and 50% by weight,preferably between 15% and 40% by weight, of monovinylaromatichydrocarbon.

The elastomer is advantageously chosen from random or block copolymersof styrene and of a conjugated diene, such as butadiene, isoprene,chloroprene, carboxylated butadiene or carboxylated isoprene. Random orblock copolymers of styrene and butadiene will preferably be chosen.

The elastomer can consist of one or more copolymers chosen from blockcopolymers, with or without a random hinge, of styrene and butadiene, ofstyrene and isoprene, of styrene and chloroprene, of styrene andcarboxylated butadiene or of styrene and carboxylated isoprene.

Preferably, the copolymer of styrene and of conjugated diene is chosenfrom di- or triblock copolymers of styrene and butadiene, of styrene andisoprene, of styrene and carboxylated butadiene or of styrene andcarboxylated isoprene which have styrene contents and weight-averagemolecular weights lying within the ranges defined above.

According to an alternative form, the elastomer is chosen from random orblock copolymers of styrene and butadiene including from 50% to 95% andmore particularly from 60% to 95% by weight of units resulting frombutadiene. In addition, the proportion of units having a 1,2-double bondresulting from the butadiene can advantageously be between 12% and 50%by weight of said copolymer. The elastomer can, for example, be astyrene/butadiene copolymer of high vinyl type, that is to say having acontent of 1,2-double bonds resulting from the butadiene of greater than20% by weight of said copolymer.

The sulfur-donating coupling agents which can be used are of very variednature and are chosen as a function of the elastomer to be crosslinkedin the bitumen/crosslinked polymer composition.

The sulfur-donating coupling agent is advantageously chosen from thegroup consisting of elemental sulfur, hydrocarbyl polysulfides,sulfur-donating vulcanization accelerators and the mixtures of suchproducts with one another and/or with non-sulfur-donating vulcanizationaccelerators.

The elemental sulfur capable of being used to constitute, in part or inall, the crosslinking agent is advantageously flowers of sulfur andpreferably crystalline sulfur in the orthorhombic form known under thename of alpha-sulfur.

The vulcanization accelerators are either hydrocarbyl polysulfides orsulfur-donating vulcanization accelerators or non-sulfur-donatingvulcanization accelerators. The hydrocarbyl polysulfides can be chosenfrom those which are defined in the patent FR 2 528 439 cited as exampleand/or incorporated by reference in the present patent application. Thesulfur-donating vulcanization accelerators can be chosen from thiurampolysulfides, such as, for example, tetrabutylthiuram disulfides,tetraethylthiuram disulfides and tetramethylthiuram disulfides. Thenon-sulfur-donating vulcanization accelerators which can be used can besulfur-comprising compounds chosen in particular frommercaptobenzothiazole and its derivatives, dithiocarbamates and itsderivatives and monosulfides of thiuram and its derivatives.

Mention may be made, for example, of zinc 2-mercaptobenzothiazole, zincdibutyldithiocarbamate or tetramethylthiuram monosulfide. For furtherdetails with regard to the sulfur-donating and non-sulfur-donatingvulcanization accelerators which can be used according to the invention,reference may made to the patents EP 0 360 656, EP 0 409 683 and FR 2528 439 cited as example and/or incorporated by reference in the presentpatent application.

Adhesion agents and/or surface-active agents can also be added to thebitumen/crosslinked polymer composition according to any known process.They are generally chosen from alkylamine derivatives, alkylpolyaminederivatives, alkylamidopolyamine derivatives, alkylamidopolyaminederivatives and derivatives of quaternary ammonium salts, taken alone oras a mixture. The amount of adhesion agents and/or surface-active agentsin the bitumen/crosslinked polymer composition is, for example, between0.2% and 2% by weight, preferably between 0.5% and 1% by weight, withrespect to the total weight of the bitumen/crosslinked polymercomposition.

The order of introduction of the different constituents does not appearto influence the mechanical and/or dynamic properties of thebitumen/crosslinked polymer composition thus obtained. Nevertheless, itwill be preferable to add the elastomer before or at the same time asthe sulfur-donating coupling agent for better homogeneity of thecomposition.

According to an alternative form, the elastomer and the sulfur-donatingcoupling agent can be introduced simultaneously in the form of a mothersolution, according to any known process, during the process for thepreparation of the bitumen/crosslinked polymer composition. The mothersolution generally comprises a hydrocarbon oil acting as thinning agent,from 5% to 40% by weight of elastomer and from 0.02% to 15% by weight ofcoupling agent, preferably from 10% to 35% by weight of elastomer andfrom 0.1% to 5% by weight of coupling agent.

The bitumen/crosslinked polymer compositions can be used as is or elsediluted, according to any known process, with variable proportions ofbitumen or of a composition according to the invention having differentcharacteristics, in order to form bitumen/polymer binders having achosen content of crosslinked elastomer which can either be equal to(undiluted composition) or else less (diluted composition) than thecontent of crosslinked elastomer of the corresponding initialbitumen/polymer compositions.

Generally, the diluting of the bitumen/crosslinked polymer compositionscan be carried out either directly subsequent to the obtaining of saidcompositions, when a virtually immediate use of the resultingbitumen/polymer binders is required, or else after a more or lessprolonged duration of storage of the bitumen/crosslinked polymercompositions, when a delayed use of the resulting bitumen/polymerbinders is envisaged. The bitumen for the diluting of abitumen/crosslinked polymer composition according to the invention canbe chosen from the bitumens described above. If appropriate, the bitumenused for the diluting may have been itself pretreated with an acidicadjuvant and/or a H₂S scavenger according to the invention.

The bitumen/crosslinked polymer compositions obtained by the preparationprocess described above have improved mechanical and dynamic properties,in particular a reinforced multigrade nature. Reinforced multigradenature is understood to mean the fact that these bitumen/crosslinkedpolymer compositions exhibit a broad plasticity interval. Said intervalis defined as the difference between the ring-and-ball softeningtemperature, which reveals the properties under hot conditions of thebinder or bitumen/polymer composition, and the Fraass breaking point,which reveals the properties under cold conditions of thebitumen/crosslinked polymer composition. The bituminous binderconsisting of/or based on the bitumen/crosslinked polymer compositionwill show better resistance to the stresses under hot conditions andunder cold conditions as the plasticity interval widens.

More generally, the bituminous compositions obtained by the preparationprocess according to the present invention exhibit improved mechanicaland dynamic properties, in particular a better consistency, with a lowerneedle penetrability at 25° C. and/or a higher ring-and-balltemperature.

In addition, at the temperatures of preparation and/or of use(transportation, loading, unloading and storage) conventionally ofbetween 90° C. and 200° C., the H₂S emissions originating from thebituminous compositions, in particular from the bitumen/crosslinkedpolymer compositions according to the invention, are greatly reduced.The content of H₂S emitted is in particular less then 10 ppm, morepreferably less than or equal to 1 ppm, the content of H₂S beingmeasured according to a conventional method for the assaying of H₂S inthe liquid phase.

Various uses of the bituminous compositions obtained according to theinvention are envisaged. In particular, the bituminous compositions, inparticular the bitumen/polymer compositions and the bitumen/crosslinkedpolymer compositions, according to the invention can be used in thepreparation of bituminous binders.

According to a specific embodiment, a bituminous binder comprises abituminous composition as described above.

The bituminous binder according to the invention can in its turn beemployed to prepare a combination with aggregates, in particular roadaggregates.

As regards the road applications, the invention is targeted inparticular at bituminous mixes as materials for the construction and themaintenance of road foundations and their surfacing, and also incarrying out all road works.

Bituminous mix is understood to mean a mixture of a bituminous binderwith aggregates and optionally inorganic and/or synthetic fillers.

The bituminous mix comprises a bituminous binder as described above andoptionally inorganic and/or synthetic fillers, preferably chosen fromfines, sand, stone chips and recycled milled products. The aggregatesare inorganic and/or synthetic aggregates, in particular recycled milledproducts, with dimensions of greater than 2 mm, preferably of between 2mm and 20 mm.

The bituminous binder described above can advantageously be used toprepare a surface coating, a hot bituminous mix, a cold bituminous mix,a cold-poured bituminous mix or a grave emulsion.

As regards the road applications, the invention is also targeted atasphalts as materials for constructing and covering sidewalks.

Asphalt is understood to mean a mixture of bituminous binder withinorganic and/or synthetic fillers.

An asphalt comprises a bituminous binder as described above andinorganic fillers, such as fines, sand or stone chips, and/or syntheticfillers. The inorganic fillers are composed of fines (particles withdimensions of less than 0.063 mm), of sand (particles with dimensions ofbetween 0.063 mm and 2 mm) and optionally of stone chips (particles withdimensions of greater than 2 mm, preferably of between 2 mm and 4 mm).

The asphalts exhibit 100% compactness and are mainly used to constructand cover sidewalks, whereas the mixes have a compactness of less than100% and are used to construct roads. Unlike the mixes, the asphalts arenot compacted with a roller when being put in place.

Another aspect of the invention is the use of a bituminous composition,preferably a bitumen/crosslinked polymer composition, in variousindustrial applications, in particular for preparing a leaktightcoating, a membrane or a seal coat.

As regards the industrial applications of the bituminous compositions,mention may be made of the preparation of leaktight membranes, ofnoise-reduction membranes, of insulating membranes, of surface coatings,of carpet tiles or of seal coats.

Examples

The invention is illustrated by the following examples, given withoutimplied limitation.

In these examples, the amounts and percentages are expressed by weight,unless otherwise indicated.

For the record, throughout the present patent application, the followingproperties of the bitumens are measured as shown in table 1 below:

TABLE 1 Measurement Property Abbreviation Unit standard Needlepenetrability at 25° C. P25 1/10 mm EN 1426 Ring-and-ball softening RBT° C. EN 1427 temperature Fraass breaking point Fraass ° C. EN 12593

Bitumen

The bitumen used results from vacuum residues from the directdistillation of crude oil. The bitumen has a P25 of 43 1/10 mm.

Elastomer

Styrene/butadiene/styrene block copolymer, comprising 30.5% by weight ofstyrene and comprising 69.5% by weight of butadiene. The content of1,2-vinyl groups is 27.8% by weight, with respect to the total weight ofcopolymer. The copolymer has a weight-average molecular weight (Mw) of142 500 daltons and a polydispersity index I_(p) of 1.09.

Acidic Adjuvant

115% Polyphosphoric acid, denoted PPA; CAS No. 8017-16-1.

Sulfur-Donating Coupling Agent

Flowers of sulfur; CAS No. 7704-34-9.

Scavenger

The characteristics of the different scavengers S_(x) tested are listedin the following table 2:

TABLE 2 Reference of the Trade scavenger S_(x) Product name/Supplier CASNo. S₁ Zinc carboxylate Nalco S₂ Copper(II) hydroxy Merck 12069-69-1carbonate S₃ Magnesium hydroxy VWR International 12125-28-9 carbonate S₄Calcium carbonate Sigma-Aldrich 471-34-1 S₅ Zinc oxide VWR International1314-13-2 S₆ Calcium oxide Aldrich 1305-78-8 S₇ Magnesium oxide VWRInternational 1309-48-4 S₈ Copper(II) oxide VWR International 1317-38-0Bitumen/Crosslinked Polymer Compositions C₁ to C₈

The bitumen/crosslinked polymer compositions C₁ to C₈ are preparedaccording to a preparation process employing the following three stages:

First Stage: Preparation of the Bitumen/Crosslinked Polymer Compositionswithout PPA: C°₁ to C°₉

The following are introduced into the reactor:

97.71% by weight of the bitumen,

2.22% by weight of the elastomer.

The mixture is stirred at high intensity, that is to say at a high shearrate, in order to obtain a mixture which is homogeneous at the micronscale, and is heated at 185° C. for approximately 4 hours.

0.07% by weight of the sulfur-donating coupling agent is subsequentlyadded.

The mixture is stirred at low intensity and is heated at 185° C. for 2hours.

The percentages of each of the constituents are calculated with respectto the weight of the bitumen/crosslinked polymer composition resultingfrom the first stage.

Second Stage: Treatment of the H₂S Emissions in Order to ObtainBitumen/Crosslinked Polymer Compositions without PPA but with ScavengerC^(s) ₁ to C^(s) ₉

The second stage consists in adding 0.2% by weight of the scavengerS_(x). The scavenger S_(x) is introduced into the reactor and then themixture is stirred while maintaining the temperature at 185° C. for 20minutes. The percentage of scavenger S_(x) is calculated with respect tothe weight of the bitumen/crosslinked polymer composition resulting fromthe second stage.

For the compositions C^(s) ₁ to C^(s) ₈, the scavenger S_(x) was addeddirectly to the reactor, without predissolution.

For the composition C^(s) ₉, the scavenger S₂ was added as a 20% byweight solution in a mineral oil.

Third Stage: Acid Treatment with PPA in Order to ObtainBitumen/Crosslinked Polymer Compositions with PPA and Scavenger C₁ to C₈

The third stage consists in adding 0.8% by weight of PPA to the reactionmedium. The PPA is introduced into the reactor and then the mixture isstirred while maintaining the temperature at 185° C. for 30 minutes. Thepercentage of PPA is calculated with respect to the weight of thebitumen/crosslinked polymer composition resulting from the third stage.

The amounts used are as follows: 967.3 g of bitumen, 22 g of theelastomer, 0.7 g of sulfur, 2 g of scavenger S_(x) and 8 g of PPA.

Measurement of the H₂S Emissions

The measurement of the H₂S emissions is carried out according to aconventional method for assaying H₂S. The measurement of the H₂Semissions consists in sparging gaseous nitrogen into thebitumen/crosslinked polymer composition to be tested, maintained at 185°C., followed by the measurement of the content of H₂S trapped in thegaseous nitrogen by means of a H₂S gas detector. The calculation of theconcentration of H₂S in the liquid phase is based on the initial weightof the bitumen/crosslinked polymer composition tested.

This measurement does not have the purpose of being representative ofthe content of H₂S present in the gaseous headspace in real time but hasthe aim of comparing the effectiveness of the scavengers used underidentical conditions, by determining the presence or the absence of arelease of H₂S. Thus, we have set a limiting threshold for release ofH₂S above which we consider that the effectiveness of the scavenger isinsufficient. This method makes it possible, in addition, to demonstratethe phenomenon of deactivation of certain scavengers in the presence ofan acidic adjuvant.

The measurement of the H₂S emissions is carried out after each of thethree stages described above. The results are listed in table 3 below.

TABLE 3 PmB + S_(x) + PmB PmB + S_(x) PPA H₂S H₂S H₂S Cº_(x) (ppm) C^(s)_(x) (ppm) C_(x) (ppm) Cº₁ >100 C^(s) ₁   <1* C₁ >100 Cº₂ >100 C^(s) ₂  <1* C₂   <1* Cº₃ >100 C^(s) ₃ >100 C₃ >100 Cº₄ >100 C^(s) ₄ >100C₄ >100 Cº₅ >100 C^(s) ₅ >100 C₅ >100 Cº₆ >100 C^(s) ₆ >100 C₆ >100Cº₇ >100 C^(s) ₇ >100 C₇ >100 Cº₈ >100 C^(s) ₈   <1* C₈   <1* Cº₉ >100C^(s) ₉   <1* C₉   <1* *detection limit of the H₂S gas detector

In the light of the results gathered together in table 3, the followingcomments may be made:

-   -   During the first stage of the process for the preparation of the        bitumen/polymer composition C°_(x), the crosslinking with sulfur        of the elastomer is accompanied by a release of H₂S. The        contents of H₂S measured exceed the limiting threshold of 100        ppm.    -   During the treatment of the second stage, the scavengers S₁ to        S₈ can be differentiated according to their effectiveness in        trapping and/or neutralizing the H₂S. For the        bitumen/crosslinked polymer composition C^(s) ₃, C^(s) ₄, C^(s)        ₅, C^(s) ₆, or C^(s) ₇, the addition, respectively, of 0.2% by        weight of the scavenger S₃, S₄, S₅, S₆ or S₇ is not sufficient        to reduce the release of H₂S to a content of less than 100 ppm.        The scavengers S₃, S₄, S₅, S₆ and S₇ consequently prove to be        scavengers which are relatively ineffective in reducing H₂S        emissions in bitumen/crosslinked polymer compositions.    -   On the other hand, the scavengers S₁, S₂ and S₈ are particularly        effective. Success is achieved in reducing the H₂S emissions of        the bitumen/crosslinked polymer compositions C^(s) ₁, C^(s) ₂        and C^(s) ₈ down to a content below the detection limit of the        H₂S gas detector (1 ppm).

Furthermore, it is noticed that the addition of the scavenger S₂ insolution in a mineral oil does not damage the effectiveness of saidscavenger in reducing the H₂S emissions of the bitumen/crosslinkedpolymer composition C^(s) ₉.

-   -   During the acid treatment of the third stage, the measured        content of H₂S in the bitumen/crosslinked polymer composition C₁        is, surprisingly, markedly greater than the limiting threshold        of 100 ppm, whereas the measurement carried out after the second        stage on the bitumen/crosslinked polymer composition C^(s) ₁ had        revealed virtually no presence of H₂S (<1 ppm). This increase in        the content of H₂S before and after the third stage (20 min        after the introduction of the PPA) reflects a phenomenon of        release of H₂S responsible for the deactivation of the scavenger        S₁.

In addition, this phenomenon of release of H₂S is also observed for thebitumen/crosslinked polymer compositions C^(s) ₃, C^(s) ₅ and C^(s) ₆respectively comprising the scavengers S₃, S₅ and S₆. This is because asignificant increase in the content of H₂S (ΔH₂S≥100 ppm) is observedbefore and after the third stage (30 min after the introduction of thePPA).

Thus, the results demonstrate that the addition of PPA deactivates thescavengers S₁, S₃, S₅ and S₆ and produces a phenomenon of release of H₂Sin the bitumen/crosslinked polymer compositions C₁, C₃, C₅ and C₆.

For the bitumen/crosslinked polymer compositions C^(s) ₄ and C^(s) ₇respectively comprising the scavengers S₄ and S₇, it is not possible togo by these measurements in ruling on the presence of a phenomenon ofdeactivation of the scavenger by the PPA insofar as the scavengers S₄and S₇ are not effective enough as H₂S scavenger.

-   -   The effectiveness of the scavengers S₂ and S₈ is particularly        noteworthy in the presence of PPA since success is achieved in        suppressing virtually all of the H₂S emissions in the        bitumen/crosslinked polymer compositions C₂ and C₈.

In addition, the presence of PPA does not damage the effectiveness ofthe scavengers S₂ and S₈ as a phenomenon of release of H₂S in thebitumen/crosslinked polymer compositions C₂ and C₈ is not observed. Thescavengers S₂ and S₈ are thus compatible with an acid treatment ofbitumen/crosslinked polymer composition, in particular a treatment withPPA.

Furthermore, the effectiveness of the scavenger S₂ is maintained aftertreatment with PPA when said scavenger is added in solution in a mineraloil (bitumen/crosslinked polymer composition C₉).

In conclusion, the inorganic or organic copper salts are particularlyeffective in comparison with the other inorganic or organic metal saltsas H₂S scavenger of bitumen/crosslinked polymer compositions employingan acid treatment, in particular a treatment with PPA.

Properties of the Bitumen/Crosslinked Polymer Composition

The characteristics of the different bitumen/crosslinked polymercompositions, measured according to the abovementioned standards, arerecorded in the following table 4:

TABLE 4 Bitumen/crosslinked polymer composition C^(s) ₁ C₁ C₂ C₈ H₂Sscavenger S₁ S₁ S₂ S₈ PPA presence no yes yes yes yes/no P25 ( 1/10 mm)34 31 27 28 RBT (° C.) 62 65.4 68.4 66.8 Fraass (° C.) −8 −12 −10 −9Plasticity interval (ΔRBT- 70 77.4 78.4 75.8 Fraass)

The comparison of the RBT and Fraass results of the bitumen/crosslinkedpolymer compositions C^(s) ₁ and C₁ confirms the increase in theplasticity interval due to the acid treatment with PPA described in theprior art.

The use of the scavengers S₂ and S₈ according to the present inventiondoes not affect the effect of the acid treatment on the mechanical anddynamic properties of the bitumen/crosslinked polymer composition, inparticular on the plasticity interval. On the contrary, thebitumen/crosslinked polymer composition C₂ has a plasticity intervalwidened in comparison with that of the bitumen/crosslinked polymercomposition C₁. With regard to the plasticity interval of thecomposition C₈, it remains comparable to that of the composition C₁.

Use of a Package of H₂S Scavenger/Acidic Adjuvant Additives: Effect onthe H₂S Emissions and on the Properties of the Bitumen/CrosslinkedPolymer Compositions

Preparation of the Packages of Additives P₂ and P₈:

Two packages of additives P₂ and P₈ are prepared by mixing 20% by weightof scavenger S₂ (package P₂) or S₈ (package P₈) and 80% by weight ofPPA. The scavengers S₂ and S₈ are soluble in the PPA and the packages ofadditives P₂ and P₈ are provided in the form of a homogeneous solution.

Preparation of the Bitumen/Crosslinked Polymer Compositions C′₂ and C′₈:

Bitumen/crosslinked polymer compositions C′₂ and C′₈ were prepared byrespectively adding the package of additives P₂ (composition C′₂) or P₈(composition C′₈) to the bitumen/crosslinked polymer composition C°₂ orC°₈ obtained on conclusion of the first stage as described above.

Measurement of the H₂S Emissions:

The measurement of the H₂S emissions is carried out after thepreparation of the bitumen/crosslinked polymer composition (first stage)and after the addition of the package of additives. The results arelisted in table 5 below.

TABLE 5 PmB + Package PmB of additives Cº_(x) H₂S (ppm) C_(x) H₂S (ppm)Cº₂ >100 C′₂ <1* Cº₈ >100 C′₈ <1*

In the light of the preceding results, it is noticed that the additionof the package of additives P₂ or P₈ on conclusion of the first stage ofthe process for the preparation of the bitumen/crosslinked polymercomposition C°₂ or C°₈ does not damage the effectiveness of thescavenger in trapping the H₂S emissions. This is because a phenomenon ofrelease of H₂S in the bitumen/crosslinked polymer compositions C′₂ andC′₈ is not observed. The scavengers S₂ and S₈ and the PPA can thus beintroduced all at once in the form of a package of additives, whichmakes it possible to shorten the duration of preparation of abitumen/crosslinked polymer composition while reducing the H₂Semissions.

Properties of the Bitumen/Crosslinked Polymer Comoositions:

The characteristics of the different bitumen/crosslinked polymercompositions, measured according to the abovementioned standards, arelisted in the following table 6:

TABLE 6 Bitumen/crosslinked polymer composition C₁ C₂ C₈ C′₂ C′₈ H₂Sscavenger S₁ S₂ S₈ S₂ S₈ PPA presence yes yes yes yes yes yes/no P25 (1/10 mm) 31 27 28 23 22 RBT (° C.) 65.4 68.4 66.8 71 70.4 Fraass (° C.)−12 −10 −9 −10 −10 Plasticity interval (ΔRBT-Fraass) 77.4 78.4 75.8 8180.4

The addition of the package of additives P₂ or P₈ does not affect theeffect of the acid treatment on the mechanical and dynamic properties ofthe bitumen/crosslinked polymer composition, in particular on theplasticity interval. On the contrary, the bitumen/crosslinked polymercompositions C′₂ and C′₈ have a plasticity interval widened incomparison with that of the bitumen/crosslinked polymer composition C₁.

In conclusion, the process for the preparation of thebitumen/crosslinked polymer compositions according to the inventionmakes it possible to substantially reduce the releases of hydrogensulfide (H₂S) in the presence of an acidic adjuvant, while havingmechanical and dynamic properties comparable to those of thebitumen/crosslinked polymer compositions of the prior art.

1. A package comprising: (1) a bituminous composition, (2) an acidicadjuvant chosen from phosphoric acids, polyphosphoric acids and theirmixtures, and (3) from 0.05% to 5% by weight of a H₂S scavengercomprising copper oxides, the percentages being calculated with respectto the total weight of the bituminous composition.
 2. The package asclaimed in claim 1, which further comprises at least one H₂S scavengerselected from the group consisting of copper hydroxides, copperhydrates, copper hydroxy carbonates, copper carbonates, coppercarboxylates, copper nitrates and copper phosphates and their mixtures.3. The package as claimed in claim 1, wherein the ratio by weight of theH₂S scavenger with respect to the acidic adjuvant is between 1:300 and100:1.
 4. The package as claimed in claim 3, wherein the ratio by weightof the H₂S scavenger with respect to the acidic adjuvant is between 1:10and 10:1.
 5. The package as claimed in claim 4, wherein the ratio byweight of the H₂S scavenger with respect to the acidic adjuvant isbetween 1:10 and 5:1.
 6. The package as claimed in claim 1, whichfurther comprises one or more inert solvents.
 7. The package as claimedin claim 6, wherein the solvent is a mineral oil.
 8. The package asclaimed in claim 6, wherein the amount of solvent is between 1% and 95%by weight, with respect to the total weight of the acidic adjuvant andthe H₂S scavenger.
 9. The package as claimed in claim 8, wherein theamount of solvent is between 10% and 90% by weight, with respect to thetotal weight of the acidic adjuvant and the H₂S scavenger.
 10. Thepackage as claimed in claim 9, wherein the amount of solvent is between20% and 80% by weight, with respect to the total weight of the acidicadjuvant and the H₂S scavenger.
 11. The package as claimed in claim 10,wherein the amount of solvent is between 40% and 60% by weight, withrespect to the total weight of the acidic adjuvant and the H₂Sscavenger.
 12. The package as claimed in claim 1, wherein it consistssolely of the bitumen or bituminous composition, the H₂S scavenger andthe acidic adjuvant.
 13. The package as claimed in claim 1, wherein thebituminous composition, the acidic adjuvant and the H₂S scavenger arepacked separately.
 14. The package as claimed in claim 1, comprisingfrom 90% to 99.3% by weight of bitumen, with respect to the total weightof the bituminous composition.
 15. A process for preparation of abitumen or a bituminous composition, said process comprising a stage oftreatment of a bitumen or a bituminous composition with: from 0.05% to5% by weight of a H₂S scavenger selected from the group consisting ofcopper oxides and their mixtures with a copper compound wherein thecopper compound is selected from the group consisting of copperhydroxides, copper hydrates, copper hydroxy carbonates, coppercarbonates, copper carboxylates, copper nitrates, copper phosphates andtheir mixtures, and an acidic adjuvant chosen from phosphoric acids,polyphosphoric acids and their mixtures, the percentages beingcalculated with respect to the total weight of the bituminouscomposition.
 16. The process as claimed in claim 15, wherein the H₂Sscavenger and the acidic adjuvant are used separately.
 17. The processas claimed in claim 15, wherein the H₂S scavenger and the acidicadjuvant are directly added to the bituminous composition in the form ofa package of additives.
 18. A process for preparation of abitumen/crosslinked polymer composition comprising employing asulfur-donating coupling agent and a stage of treatment of a bitumen ora bituminous composition with: from 0.05% to 5% by weight of a H₂Sscavenger selected from the group consisting of copper oxides and theirmixtures with a copper compound wherein the copper compound is selectedfrom the group consisting of copper hydroxides, copper hydrates, copperhydroxy carbonates, copper carbonates, copper carboxylates, coppernitrates, copper phosphates and their mixtures, and an acidic adjuvantchosen from phosphoric acids, polyphosphoric acids and their mixtures,the percentages being calculated with respect to the total weight of thebitumen/crosslinked polymer composition.
 19. The process as claimed inclaim 18, wherein the proportion of acidic adjuvant is between 0.05% and15% by weight, the percentages by weight being calculated with respectto the total weight of the bitumen/crosslinked polymer composition. 20.The process as claimed in claim 18, wherein the proportion of H₂Sscavenger is between 0.1% and 1% by weight, the percentages by weightbeing calculated with respect to the total weight of thebitumen/crosslinked polymer composition.